Rheological Properties of High-Viscosity Solutions of Long Molecules

UNDER the above heading, we presented a note in Nature1 in which we directed attention to certain peculiar phenomena observed with concentrated solutions of rubber or of aluminium soaps in hydrocarbons and gave an explanation. These phenomena concerned secondary flows, high inlet losses for flow in pipes, existence of retardation layers with flow in small-diameter pipes and an increase in the surface energies of these systems when they are strained. It was noticed that the free energy of these systems increased on straining. Due to absence of experimental data, this increase in free energy was ascribed to a decrease in entropy, in analogy with the kinetic theory of rubber elasticity.